A Sneak Attack By Grey Worm
Meanwhile, all the way down in Casterly Rock, it seems that Grey Worm is leading an ambush on Lannister territory. As a reminder, Tyrion was in charge of overseeing the sewer system when he was on duty. Could he be the one behind this attack? In a later shot, we see a handful of the Unsullied letting more of their own men in through some gates. This could be some Trojan War kind of sneakiness.